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Thu, 5 Aug 2021 15:20:09 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id iKHzGakBDGFDdQAAMHmgww (envelope-from ); Thu, 05 Aug 2021 15:20:09 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v4 29/35] mm: slub: Move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context Date: Thu, 5 Aug 2021 17:19:54 +0200 Message-Id: <20210805152000.12817-30-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210805152000.12817-1-vbabka@suse.cz> References: <20210805152000.12817-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=QZCWRjka; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=ns+W+YCW; dmarc=none; spf=pass (imf12.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Stat-Signature: fg1atoyqc3ichio487w5p3dpoigujfku X-Rspamd-Queue-Id: 8FDF710003C3 X-Rspamd-Server: rspam01 X-HE-Tag: 1628176810-907264 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Sebastian Andrzej Siewior flush_all() flushes a specific SLAB cache on each CPU (where the cache is present). The deactivate_slab()/__free_slab() invocation happens within IPI handler and is problematic for PREEMPT_RT. The flush operation is not a frequent operation or a hot path. The per-CPU flush operation can be moved to within a workqueue. [vbabka@suse.cz: adapt to new SLUB changes] Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Vlastimil Babka --- mm/slub.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 48 insertions(+), 8 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index dceb289cb052..da48ada3d17f 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2513,33 +2513,73 @@ static inline void __flush_cpu_slab(struct kmem_c= ache *s, int cpu) unfreeze_partials_cpu(s, c); } =20 +struct slub_flush_work { + struct work_struct work; + struct kmem_cache *s; + bool skip; +}; + /* * Flush cpu slab. * - * Called from IPI handler with interrupts disabled. + * Called from CPU work handler with migration disabled. */ -static void flush_cpu_slab(void *d) +static void flush_cpu_slab(struct work_struct *w) { - struct kmem_cache *s =3D d; - struct kmem_cache_cpu *c =3D this_cpu_ptr(s->cpu_slab); + struct kmem_cache *s; + struct kmem_cache_cpu *c; + struct slub_flush_work *sfw; + + sfw =3D container_of(w, struct slub_flush_work, work); + + s =3D sfw->s; + c =3D this_cpu_ptr(s->cpu_slab); =20 if (c->page) - flush_slab(s, c, false); + flush_slab(s, c, true); =20 unfreeze_partials(s); } =20 -static bool has_cpu_slab(int cpu, void *info) +static bool has_cpu_slab(int cpu, struct kmem_cache *s) { - struct kmem_cache *s =3D info; struct kmem_cache_cpu *c =3D per_cpu_ptr(s->cpu_slab, cpu); =20 return c->page || slub_percpu_partial(c); } =20 +static DEFINE_MUTEX(flush_lock); +static DEFINE_PER_CPU(struct slub_flush_work, slub_flush); + static void flush_all(struct kmem_cache *s) { - on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1); + struct slub_flush_work *sfw; + unsigned int cpu; + + mutex_lock(&flush_lock); + cpus_read_lock(); + + for_each_online_cpu(cpu) { + sfw =3D &per_cpu(slub_flush, cpu); + if (!has_cpu_slab(cpu, s)) { + sfw->skip =3D true; + continue; + } + INIT_WORK(&sfw->work, flush_cpu_slab); + sfw->skip =3D false; + sfw->s =3D s; + schedule_work_on(cpu, &sfw->work); + } + + for_each_online_cpu(cpu) { + sfw =3D &per_cpu(slub_flush, cpu); + if (sfw->skip) + continue; + flush_work(&sfw->work); + } + + cpus_read_unlock(); + mutex_unlock(&flush_lock); } =20 /* --=20 2.32.0